Automatic timing mechanism for fuel injection pumps



F'eb- 1941; F. EIDEITIEIER 2, 30, 7

AUTOMATIC TIMING MECHANISM FOR FUEL INJECTION PUMPS Filed llarch 7. 1940 v 2 Sheets-Sheet l Attorney Feb. 4, 1941. F. EIDEQEIER AUTOMATIC TIMING MECHANISM FOR FUEL INJECTION PUMPS Filed March '7. 1940 2 Sheets-Sheet 2 i In veng'or [7/72 Ede/2e 9,-

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Attorney Patented Feb. 4, 1941 UNITED STATES AUTOMATIC TIMING MECHANISM FOR FUEL INJECTION PUMPS Fritz Eideneier, Stuttgart, Germany, assignor to Robert Bosch Application In G Gesellschaft mit Haftung, Stuttgart, Germany March '1, 1940, Serial No. 322,677 crmany February 9, 1939 beschrankte 12 Claims. (CL 123-140) This invention relates to automatic timing mechanisms for fuel injection pumps for internal combustion engines, and particularly to such mechanisms in which a member, such as a pivoted vane, forms a movable partition between two chambers connected to the fuel supply system of the'pump, and communicating with each other through a normally stationary restricted passage which developes a pressure diflerence in the chambers in accordance with an operating characteristic of the engine to move the member to predetermined positions of rest and thereby advance or retard the cam shaft of the pump relatively to the engine shaft driving it.

The primary object of the invention is to provide a simple, inexpensive and compact hydraulic mechanism of this kind which can be readily associated with and disassembled from timing adjusting mechanism for the pump drive. This and other objects will be obvious from the accompanying drawings taken in connection with the following description thereof. In these drawings showing the preferred embodiment of the inven tion,

Figure 1 shows an injection pump to which a device according to the invention is attached;

Fig. 2 is a longitudinal section of the device on the line IIlI, of Fig. 3;

Fig. 3 is a cross section on the line III-III, of Fig. 2;

Fig. 4 is an oblique view of the device; and

Figs. 5 to 8 are detail views, in which Fig. 8

embodies a modification.

The camshaft2 of the injection pump is driven from an internal combustion engine, not shown, by a shaft 34 and a coupling 33, 29. The

, casing of the pump contains four separate pumps,

not shown, from which separate pressure pipes 3 lead to the various cylinders of the engine. The

fuel feed pump 4 is driven by the cam shaft 2 and draws fuel through the pipe 5 from a tank 3.

A pressure pipe 36 leads from the feed pump 4 to a. filter 1 and thence through a casing 3 and a pipe 31 to a. suction chamber 9 common to all fuel injection pumps.

As shown in Figs. 2 and 3, a vane II is keyed on a shaft |li in the casing 8 which is closed by a cover l2, so that the inner space of the casing 8 is subdivided by the vane into two chambers l3 and M which communicate exclusively through the medium of a narrow restricted passage l5. This passage is formed by a recess in the front surface of a ring l6 inserted in a corresponding recess of the cover I2 and secured against rotation by a pin l'l fitting therein.

Each of two levers or transmission members l3 secured to the ends of the shaft l embraces with its ,free open end a pin |9 of a yoke 20 inserted in an annular groove of an adjustingsleeve 2| which with opposite teeth 22 of steep pitch engages corresponding grooves 32 on the outside of a bushing 23, Figs. 6 and 7, and which upon longitudinal displacement-turns relatively to the bushing 23.

The bushing 23, as indicated in Fig. 2, is held tight on the conical end portion 24 of the camshaft 2 by a nut 25 having a washer 23. A coupling member 29 provided with dogs 30 on one side has a collar 23 for engaging with slight longitudinal play the annular space formed between the right-hand front side of the washer 26 and a shoulder 21 of the bushing 23. On its other front side the member 29 has two doglike projections 3|, Figs. 3, 5, which extend over the entire length of the bushing 23 and on which the adjusting sleeve 2| is longitudinally displaceably yet non-rotatably guided by recesses 54, Fig. 7. As the sleeve 2| can only be longitudinally displaced relatively to the coupling member 29 but is rotatable also relatively to the bushing 23,

- longitudinal displacement of the sleeve will therefore result in a rotation of the cam shaft 2 with respect to the driving shaft 34. In this way, variation of the time of injection is effected.

Assume that a, motion of the adjusting sleeve 2| to the left, Fig. 2, causes an advance of the beginning of injection. This motion of the sleeve 2| to the left is performed against the action of a spring abutting against the sleeve 2| and the coupling member 29. How the motion of the sleeve against the action of this spring is carried out will be explained below.

The fuel delivered by the pump 4 passes through the pressure pipe 33 into the chamber 4o 13 at 33 indicated. by a dot and dash line in Fig. 2

whence it flows through the restricted passage I5, Fig. 3, into the chamber l4. From this chamber l4 the fuel flows into the pipe 31 at 39, also indicated by a dot and dash line in Fig. 2. Now

assume that the injection pump is built in the known manner, wherein each pump unit thereof at each suction stroke takes a uniform amount of fuel out of the common suction space 9 and a return flow space 40, Fig. 1, separated in Fig. 1,

an overflow pipe 42 connected with the pressure pipe 36 by a check valve. 43.

By setting the check valve 43 to a certain opening pressure the pressure in the pipe 36 and in the chamber l3, Fig. 2, is kept continually constant. The liquid pressure in the other chamber I4 is not constant, however, but decreases with increasing speed of the engine, since this chamber communicates through the pipe 31 with the suction space 9 and the withdrawal of fuel from this space by the pump units is greater per time unit at high than at low speeds. Since the pressure drop in the restricted passage increases with the flow of fuel therethrough in a unit of time, the difference in pressure between the two chambers l3 and i4 increases therefore with increasing speed and tends to move the vane II to the right in Fig. 2, and the more so the higher the speed is. As indicated in Fig. 8, the opening I5 is preferably so dimensioned that when the member ll occupies positions more to the right its free cross section at a, corresponding to the greater amount of flow at high speeds, is greater than in positions more to the left, as at b.

As the vane I I is connected with the adjusting sleeve II by the shaft I0 and the forked lever l8, clockwise motion of the vane N, Fig. 2, causes the sleeve 2| to be moved to the left against the action of the spring 35, and the time of injection to be advanced, more and more as the speed of the engine increases. Upon decreasing speed the pressure in the suction space of the injection pump i increases and the spring 35 accordingly moves the sleeve 2| to the right, whereby the beginning of injection is retarded.

Insteadof using the pin ll, Fig. 3, which secures the ring l6 against rotation, it is possible also, as shown in the lower portion of Fig. 8, to provide a portion of the ring I! with teeth I! to be engaged by arack, not shown, adjustablefrom outside the casing for varying at will the cross section of the opening ii.

In an injection pump in which the suction chamber 9 and the return space 40 are combined to form a. single space, pressure in the pipe 31 varies in response to both speed and load, and the time of injection will be varied accordingly. In the practical operation of a large number of internal combustion engines the advance of the beginning of injection at increasing speed and load effected in the manner indicated has given perfect satisfaction.

In the example of construction described Figs.

ing line. The lower section 49 has an eye 5|- through which the coupling member 29 projects in an oiltight manner. S ews 5| fasten the timing device8, 49 to the injection pump I in such manner as to avoid interference with the removal of the casing 8 together with the forked lever l8. In the bottom of thesection 49 an oil I drain'plug 52 is disposed.

What is claimed is:

1. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; a. housing; a movable partition dividing said housing into two chambers one of which communicates with said fuel feed pump,

and the other of which communicates with the suction side of said injection pump; a normally stationary member having a passage which connects said chambers around said partition "in all operative positions thereof and which provides different degrees of restriction between said chambers at different positions of said partition to develop pressure differences in said chambers and thereby move said partition in accordance with the operating condition of the pumps; and

adjusting mechanism operatively connecting said partition and coupling to vary the angular relation between said cam and drive shafts.

2. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; a housing; a movable partition dividing said housing into two chambers one of which adjusting mechanism operatively connecting said partition and coupling to vary the angular relation between said cam and drive shafts.

3. In automatic'timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; a housing; a movable partition dividing said housing into two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said injection pump; a normally stationary member having a passage which connects said chambers around said partition in all operative positions thereof and which provides different degrees of restriction betwen said chambers at different positions of said partition to develop pressure differences in said chambers and thereby move said partition in accordance with the operating condition of the pumps; and adjusting mechanism, including resilient means opposing the movement of said partition in one direction, operatively connecting said partition and coupling to vary the angular relation betwe said cam and drive shafts.

4. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the-injection pump and a drive shaft of the engine; a housing; a movable partition dividing said housing into two chambers one communicating with the fuel feed pump and the other with a suctionport of the injection pump; a normally stationary member having a passage which connects said chambers around said partition in all operative positions thereof and which provides different degrees of restriction between said chambers at different positions of said partition to .develop pressure differences in said chambers and thereby move said partition in accordance with an operating characteristic of the I pump; and adjusting mechanism operatively connecting said partition and coupling to vary the angular relation between said cam and drive shaft.

5. In automatic timing mechanism for an engine-driven fuel imection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a. drive shaft of the engine; a. housing; a pivoted vane dividing said housing into two chambers one of which communicates with said fuel feed pump, and-the other of which communicates with the suction side-of said injection pump; normally stationary member having a restricte passage connecting said chambers around said vane in all operative positions thereof to develop pressure differences in said chambers and thereby move said vane in accordance with the operating condition of the pumps; and adjusting mechanism ope'ratively connecting said vane and coupling to vary the angular relation between said cam and drive shafts.

6. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaftof the engine; hydraulic mechanism comprising a housing and a pivoted vane defining therein two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said inj ction pump and also comprising a normally stationary member having a restricted passage connecting said chambers around said vane'in all operative positions thereof to develop pressure differences in said chambers and thereby move said vane .in accordance with the operating condition of the pumps; adjusting mechanism operatively connected to said coupling"; and a fork operatively connecting said hydraulic and adjusting mechanisms to vary theangular relation between said cam and drive shafts.

'7. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; hydraulic mechanism comprising a housing and a movable partition defining therein two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said injection pump, and also comprising a normally stationary member having a restricted pu e connecting said chambers around said partition in all operative positions thereof to develop pressure differences in said chambers and thereby move said partition in accordance with the operating condition of the pumps; adjusting mechanism comprising a housing and cooperative members therein arranged to vary the angular relation between said cam and drive shafts accordingly; and a transmission member connected to said hydraulic mechanism and detachably connected to said adjusting mechanism; the housing of said adjusting mechanism being attached to said pump and the housing of said hydraulic mechanism being attached to the other housing solely, whereby the hydraulic mechanism with said transmission member connected thereto may be detached from said adjusting mechanism without disconnecting the latter from the pump.

8. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of mounted on said shaft and arranged to divide said housing into two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said injection pump; a normally stationary ring surrounding said shaft for cooperation with said vane and having a recess forming a restricted passage connecting said chambers around said vane in all operative positions thereof to develop pressure diiferences in said chambers and thereby move said vane in accordance with the operating condition of the pumps; and adjusting mechanism'operatively connecting said vane and coupling to vary the angular relation between said cam and drive shafts.

9. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; a housing; a shaft in said housing; a vane mounted on said shaft and arranged to divide said housing into two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said injection pump; a normally stationary ringsurrounding said shaft for cooperation with said vane and having a recess forming a passage connecting said chambers around said vane in all operative positions thereof to develop pressure differences in said chambers and thereby move said vane in accordance with the operating condition of the pumps, said recess being of different cross section at different positions of said vane to provide different degrees of restriction between said chambers at different positions of said vane; and adjusting mechanism operatively connecting said vane and coupling to vary the angular relation between said cam and drive shafts.

10. In automatic timing mechanism for an engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaft of the injection pump and a drive shaft of the engine; a housing having a detachable cover;

condition of the pumps; and adjusting mecha-.

nism operatively connecting said vane and coupling to vary the angular relation between said cam and drive shafts.

11. In: automatic timing mechanism for an, engine-driven fuel injection pump having a fuel feed pump and a coupling connecting the cam shaftof the injection pump and a. drive shaft of the engine; a housing having a detachable cover; a shaft mounted for rotation in said housing and having a bearing in said cover; a vane mounted on said shaft and arranged to divide said housing into two chambers one of which communicates with said fuel feed pump, and the other of which communicates with the suction side of said injection pump; a ring fastened to said cover around said shaft and having a recess to form a restricted passage connecting said chambers around said vane in all operative positions thereof to develop pressure differences in said chambers and thereby move said vane in accordance with the operating condition of the pumps; and adjusting mechanism operatively connecting said vane and coupling to vary the angular relasuction side of said injection pump; a normally stationary ring surrounding said shaft and having a recess of a depth that gradually increases in one direction to form a passage of variable restriction; mid passage connecting said chambers around said vane in all operative positions thereof to develop pressure differences in said chambers and thereby move said vane in accordance with the operating condition of the pumps; and adjusting mechanism operatively connecting said 10 vane and coupling to vary the angular relation between said cam and drive shafts.

FRITZ EIDENEIER. 

